The department announced Thursday a 3 1/2-year federal investigation found the sheriff's office discriminated against Latinos with limited English-speaking ability in jails, denied them services other inmates receive and retaliated against critics.
The Sheriff's Office was given until Jan. 4 to cooperate voluntarily with the department, which would work with Sheriff Joe Arpaio to correct violations, the department said. But the Justice Department said it would file a lawsuit under the federal Civil Rights Act if the sheriff refuses to cooperate or does not reach an agreement with federal officials.
"Our case is about more than statistics. It is about real people, law abiding residents of Maricopa County who were caught up in the web of unconstitutional activity, and unlawfully stopped, detained and sometimes arrested," Assistant Attorney General Thomas E. Perez said in Phoenix. "We are not talking about isolated incidents. We found discriminatory policing that was deeply rooted in the culture of the department -- a culture that breeds a systemic disregard for basic constitutional protections."
The Justice Department found the Sheriff's Office retaliated against its critics. Perez said they "were frequently arrested and jailed for no reason, or forced to defend against specious civil complaints or other baseless charges."
Shortly after the Justice Department announced its findings, Secretary of Homeland Security Janet Napolitano issued a statement saying her department is terminating the authority of Arpaio's office under a federal agreement to screen every inmate it books for immigration status.
"Discrimination undermines law enforcement and erodes the public trust," said Napolitano, a former governor and attorney general in Arizona. "DHS will not be a party to such practices."
Arpaio, at a news conference Thursday afternoon, said the DHS decision will lead to large numbers of suspected undocumented immigrants being turned out of the county jails system and "dumped on the streets, in neighborhoods near you," The Arizona Republic reported.
He accused the federal government of using him "as a whipping post for a national, international problem."
The department said one of the nation's leading experts on racial profiling conducted a statistical analysis of Sheriff's Office traffic stops and found Latino drivers were four to nine times more likely than non-Latino drivers to be stopped in similar situations. Perez said the expert called the practice in the county "the most egregious racial profiling in the United States" that he had seen in his work.
The department found the Sheriff's Office "routinely punishes Latino inmates that are limited English-proficient and denies [them] critical services that are provided to other inmates" in violation of the Civil Rights Act of 1964, Perez said.
The department interviewed more than 400 people, reviewed thousands of pages of documents, toured jails and brought in experts.
Perez said the department is investigating other areas of "serious concern" uncovered in the investigation -- use of excessive force against Latinos, failure to provide adequate policing in Latino communities and failure to investigate allegations of sexual assaults adequately.